Flywheel magneto



June 7, 1949. PHELON 2,472,313

FLYWHEEL MAGNETO Filed June 13, 1946 INVENTOR. Russell E.P/ 1e/0rl BY ,1 ,71 wZm A TTORNE Y ture Patented 7, 1949 y. meanness ew e lx hsel emel raadima et cul to e heemagqetess an eezicr m zwithanaintemai combustion engine.

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ferred embodiment-oi the invention but it be understood that various changes may-be made 1' from the construction .shown, and that the drawme is notrto rc n m d' sd fln s r lim ting:

the scope of the invention,"theclaims forming a part of this specification beinggrelied tor, thatpurposeg V Of the drawing,

' the drawing I have shoan in detail a afge'd -,permanent mag l: l

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mean sis chas; pole-pieces;are tprovidedainas? themagnet ormasnetsewhlch procore structureu 'tion.

. instance bybeing In accordance with' the, 3 r

' tween the points view taken: alon Fig. 2 is .a view\similar'xto'figfli' but showing the rotatable field structure in adiflerent posi- Fig.4; is alulong itudinal :iiertical sectional view taken'along the'jiine 3-3 of Fig; 25-1 5 Fig. 411s a diagram of velectrical connections. {The :core structure of the magneto is nonrotat ableandi'as shown inlthe drawing, itis'carried' "by a frame 10 having a bushing fl2ewhich provides a, bearingrfor. a rotatable shaft 14.1 The shaft 14 may bean extension of the crankshaft 1 of the engine with which the magneto' is to be I used, and in anyeventitisrotated in timed rela '1' :tionship with the engine.

The core structure comprises a magnetic core: I 6 preierably 11a inated and arranged i to provide a 'plurality oi circularly ..;spaced poles. havingv arcuatefaces" which. are concentricrwith the axis or the shaftll and equidistant therefrom. 1;The1poles or the corestructure are all within an arc ot approximately *ror1e'ss and are ordinarilyat one side em ,diametral; planenthrough thef'axis of theshaft.- Primary and secondary :generatingcoils structure has three poles [8,20 and 22, andpri ber'of turns-,- as iorin stance10,000;:.='awz in a ,Y

' The-primary "coil 24 is suit my. grounded; for

' connected .to one ot-the screws" 28, 28 whichhold the core IS inplace :on "the frame Ill. he. ungroundedz end "01' theaprimary coil is connected by. means of an. insulated con! ductor 30 '"with breaker (points :32 audit; The v point-3!. is grounded and they point 32. is "carried r byra rockers arm "II."

36; pivoted; at 38. to the drame "I The; tracker arm ,35 1; has anextensionfilflar;- which is vengaged by a cam 42 mounted on .the shaft I]. Aespring serves tobias :the am 361;; to lmove the point 32 into engagement with them.v p nt 3!,

MLandthe said point'32. When .theshaft Ills rotated the cam '42 oscillates the rocker to make and breakthe'electricaliconnectlon be-j tends to the spark plug 500i the'engine. 1 l

and this, spring,' 011 antauxiliaryficon-e I ductor associated therewith, 'se rves towprovidezy. an;electrical connection ibetween athe conductor 321 and 134. :A condenser .is

connected in parallelwith the breaker. points 22 and Skin-accordance with customary practice. The secondary coil 26 is suitably grounded, for 1;;

instance by being connected with the 'samescrew 128 which is used for" grounding theprlmary; coil. Thesecondary coil is provided-"at itstungrounded end with an insulated conductor, 48 which ex-e 1 includes a flywheel which is carried by the shaft I 4 so as to be rotatable therewith. The flywheel is provided with a connecting member 52 which is formed of magnetic material, this connecting member preferably being an annular flange which surrounds the core structure, more particularly the core l6 and the coils 24 and 26 thereof. The flange 52 is carried by and preferably formed integrally with a disc-like portion 54 which is connected with the shaft l4. The flange or member 52 and the disc-like portion 54 of the rotatable unit may be formed as a unit from a single piece of magnetic material, such as steel, by a simple stamping or drawing operation. However, if preferred, a casting may be substituted.

The connecting member or flange 52 is preferably magnetically insulated from the core structure, particularly the poles thereof. As shown, such magnetic insulation is attained by providing a hub 56 of nonmagnetic material, such as brass. The hub 56 is soldered or brazed or otherwise connected with the disc-like portion 54 and is adapted to be directly engaged with the shaft l4. As shown, the end portion of the shaft I4 is tapered to flt a correspondingly tapered opening in the hub 56 and a key is provided which flts suitable keyways to insure rotation of the hub in unison with the shaft. The hub 56 is held in place by a nut 58 engaging a threaded portion of the shaft.

Carried by theconnecting member or flange 52 is at least one radially extending member and ordinarily there are two such members 60 and 62. At least one of the members is a radially charged magnet and ordinarily both of the members are magnets. The magnets are formed from a special alloy having a high coersive force. The

outer extremities of the members or magnets directly engage the internal face of the flange 52 and the said members or magnets are circularly spaced and are at one side of a diametral plane through the axis of rotation. The said members or magnets are within an arc of the flange 52 which is less than 180 and ordinarily less than 120, being thus enabled to cooperate with the relatively closely spaced poles of the core I6. The spacing is such that the two members or magnets can register simultaneously with the intermediate pole of the core structure and with one of the other poles thereof.

As stated at least one of the members 66 and 62 is a magnet, and means are provided which are connected with the inner extremity of the magnet and with the conecting member or flange 52 for providing two circularly spaced pole faces of opposite polarity which are movable in close proximity to the outer faces of the poles of the core structure and which are at one side of a diametral plane through the axis of rotation. As shown, both of the members 60 and 62 are magnets which are oppositely charged and which therefore have opposite polarity. The said means for providing pole faces of opposite polarity are pole pieces 64 and 66 carried respectively by the magnets at the'inner extremities thereof. The inner faces of the pole pieces are concentric with the axis of the shaft and are so spaced therefrom as to be adapted to move in close proximity to the pole faces I8, 20 and 22of the core i6. It will be seen that a magnetic circuit is established through the said magnets and their pole pieces and also through that portion of the flange 52 which intervenes between the two magnets.

The members or magnets 60 and 62 and their pole pieces 64 and 66 may be connected with the flange 52 by mechanical connecting means, such as rivets, but I prefer to connect them by brazing or soldering. The magnets are brazed or soldered to the flange 52 and the pole pieces are brazed or soldered to the magnets. The magnets have a critical temperature above which they cannot be heated without damage, but by using a suitable solder, such as a silver-copper alloy, and by closely controlling the temperature, soldering can be effected without damage.

A counterweight 68 is provided, this being shown as secured to the internal face of the flange or member 52 opposite the magnets by soldering or otherwise. In practice the counterweight is initially slightly heavier than the magnets and the pole pieces, and then one or more holes 10 are drilled therein in order to obtain an exact balance.

When the field structure rotates in the clockwise direction the leading pole piece 66, marked S in Fig. 1, registers with the center pole 20 of the core I6 and at the same instant the trailing pole piece '64, marked N in Fig. l, registers with the left 'pole l8 of the core 16, thus establishing a magnetic circuit through the center pole in one direction. As the field structure continues to rotate the leading pole marked S leaves the center pole 20 and comes into register with the right pole 22 of the core l6. At the same instant the trailing pole N leaves the left pole I B and comes into register with the center pole 20, as shown in Fig. 2. At this instantthe direction of the magnetic circuit through the center pole 20 is suddenly reversed and a maximum value of voltage is generated in the primary coil 24. The cam 42 is so positioned as to separate the breaker points 32 and 34 at the instant of maximum voltage in the primary coil, thus generating a high nected with the spark plug 56. In a high tension magneto it is generally desirable to maintain a relatively high remanence of flux in the magnets. In a design such as the one described this is particularly desirable because of the short length in the radial direction of the magnets relative to the area in cross section at right angles to the radial direction. This high remanence is maintained by providing adequate leakage of the flux during the portion of the rotation of the rotor when the pole pieces are not in register with the core faces. Flux leakage-is in proportion to the area of the air gap between oppositely charged surfaces. For this reason the pole pieces 64 and 66 project either axially or circularly, and preferably both axially and circularly, beyond their magnets, thus providing a larger area of air gap between one pole piece and the other oppositely charged one, and between each pole piece and the oppositely charged annular flange 52. Magnetic leakage is also indirectly proportional to the length of the air gap. For this reason the oppositely charged pole pieces are extended towards each other to approach each other as closely as possible without interfering with the effective register of the pole pieces with the faces of the poles of the stationary core.

The circular and axial projection of the pole pieces beyond their magnets is also highly important for facilitatin manufacture. As has been stated, the pole pieces are brazed or soldered to the magnets and the projection of the pole pieces beyond the magnets provides exposed faces to which the brazing or soldering material can adhere.

The magnets 60 and 62 are circularly spaced from each other to an extent greater than the width of the intermediate pole 20 of the core structure, and the pole pieces 64 and 66 project toward each other to such an extent that the width of the gap between them is less than the width of the said intermediate pole 20. Thus the spacing of the magnets is such that they cannot register simultaneously with the said intermediate pole, but the pole pieces on the magnets can register simultaneously with the said pole so as to provide a sudden reversal in the magnetic circuit through the said pole. Preferably the two magnets are of substantially the same size, but the leading pole piece 68 projects beyond the leading magnet 62 to relatively large extents and the trailing pole piece 64 projects beyond the trailing magnet 60 to smaller extents. The said leading magnet 62 has a circular width which is less than the spacing between the intermediate core pole 20 and the forward core pole I. The extents of circular projection of the pole piece 66 are such that the said pole piece can simultaneously register with both of the said core poles.

In previous designs of a flywheel magneto having a similar core structure, a single magnet was provided which was charged in the circular direction to provide two magnetic poles of opposite polarity. Such a magnet could not be placed in close proximity to any part of a flywheel made of magnetic material because the magnetism would leak from one end of the magnet to the other through the magnetic portion of the flywheel "in preference to causing flux to pass through the coil core of the core structure. The present invention eliminates this difliculty since the magnet or magnets are charged radially and the entire flywheel, or at least the magnetic portion thereof, attains a magnetic charge which is intermediate between the two poles. It is advisable, however, to insulate magnetically between the magnetic portion or flange of theflywheel and the core structure since otherwise some of the magnetism could pass from the said portion or flange to the core structure without passing through the intermediate pole of the core structure which is surrounded by the generating coils. Since a magneto embodying the invention is primarily intended for use with an internal combustion engine which usually has a crankshaft of magnetic material, it is preferable to provide magnetic spacing at some point between the flywheel, or the magnetic portion thereof, and the core structure. In the construction shown in the drawing this insulation is provided, as already described, by the use .of a hub 56 of nonmagnetic material which connects the flywheel with the shaft.

In the drawing I have shown a single pair of magnets, and I have shown a cam which separates the breaker points once during each revolution. It will be understood, however, that without departing from my invention'two or more pairs of magnets may be provided circularly spaced from each other, and that the cam may be modified to separate the breaker points two or more times during each revolution.

What I claim is:

1. A flywheel magneto for an internal combustion engine comprising in combination. a rtatable shaft, a stationary core structure adjacent the shaft including three circularly spaced poles all positioned within an arc of approximately 180 or less and havin their outer faces equidistant from the shaft axis and also including primary and secondary coils surrounding the intermediate pole, a flywheel secured to the shaft and having an annular flange formed of magnetic material and surrounding the core structure, two permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being circularly spaced within an arc of substantially less than 180 for simultaneous radial register respectively with the center pole of the core and with one of the other poles thereof and the said magnets being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of the shaft and movable in close proximity to the outer faces of the poles of the core structure which pole pieces cooperate with the magnets and with the annular flange of the flywheel to provide a, magnetic circuit having inner pole faces of opposite polarity.

2. A flywheel magneto for an internal combustion engine comprising in combination, a stationary core structure including primary and secondary coils and a plurality of circularly spaced poles havin their outer faces equidistant from an axis which poles are at one side of a diametral plane through the saidaxis, a rotatable flywheel adapted to be secured to an engine shaft rotatable about the said axis which flywheel includes an annular flange formed of magnetic material and at least partly surrounding the core structure, means for magnetically insulating the said annular flange of the flywheel from the core structure, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotation and being oppositely charged radially, and two separate circularly spaced pole pieces carried by the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of rotation and movable in close proximity to the outer faces of the poles of the core structure which pole pieces cooperate with the magnets and with the annular flange of the flywheel to provide a magnetic circuit having inner pole faces of opposite polarity,

3. A flywheel magneto for an internal combustion engine comprising in combination, a stationary core structure including primary and secondary coils and a plurality of circularly spaced poles having their outer faces equidistant from an axis which poles are at one side of a diametral 55. plane through the said axis, a rotatable flywheel adapted to be secured to an engine shaft rotatable about the said axis which flywheel includes a circularly extending connecting member formed of magnetic material, the said connecting member 60 beingv disposed radially outward from th core structure and having an internal face, means for magnetically insulating the said connecting memher from the core, structure, a radially charged permanent magnet directly engaging at its outer 66 extremity with the internal face of the connecting member, and means connected with the inner extremity of the magnet and with the connecting member and providing two circularly spaced pole faces of opposite polarity which faces are mov- 70 able in close proximity to the outer faces of the poles of the core structure and are at on side of a diametral plane through the axis of rotation.

4. The combination in a flywheel magneto for v an internal combustion engine, of a stationary magnet.

coils and a plurality of circularly spaced poles having their outer faces equidistant from an axis which poles are at one side of a diametral plane through the said axis, a rotatable flywheel formed of magnetic material and including a disc-like portion adapted to be secured to an engine shaft rotatable about the said axis which flywheel also includes an integral annular flange surrounding the core structure, means for magnetically insulating the said flywheel from the core structure, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotationand being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of rotation and movabl in close proximity to the outer faces of the poles of the core structure which pole pieces cooperate with the magnets and with the annular flangeof the flywheel to provide a magnetic circuit having irmer pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets circularly and in both directions so as to provide magnetic leakage at the ends of the said pole pieces.

5. The combination in a flywheel magneto for an internal combustion engine, of a stationary core structure including primary and secondary coils and a plurality of circularly spaced poles having their outer faces equidistant from an axis which poles are at one side of a diametral plane through the said axis, a rotatable flywheel adapted to be secured to' an engine shaft rotatable about the said axis which flywheel includes an annular flange formed of magnetic material and surrounding the core structure, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotation and being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of rotation and movable in close proximity to the outer faces of the poles of the core structure which pole pieces cooperate with the magnets and with the annular flange of the flywheel to provide a magnetic circuit having inner pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets circularly and in both directions and the pole piece on the leading magnet projecting circularly to substantially greater extents than does the pole piece on the trailing 6. The combination in a flywheel magneto for an internal combustion engine, of a rotatable shaft, a stationary core structure adjacent the shaft including three circularly spaced poles having outer faces equidistant from the axis of the shaft which poles are at one side of a diametral plane through the said axis, the said core structure also including primary and secondary generating coils surrounding the intermediate pole, a flywheel secured to the shaft and having an annular flange of magnetic material surrounding the core structure, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotation and being oppositely charged radially and the circular width of the leading magnet being less than the spacing between the intermediate core pole and the forward core pole, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of the shaft and movable in close proximity to the outer faces of the poles of the core which pole pieces cooperate with the magnets and with the annular flange of the flywheel to provide a magnetic circuit having inner pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets circularly and in both directions so as to provide magnetic'leakage at the ends of the said pole pieces and the pole piece on the leading magnet projecting circularly to such extents that it can register simultaneously with the said intermediate and forward poles of the core structure.

7. In a flywheel magneto for an internal combustion engine, the combination of a stationary core structure including three circularly spaced poles having outer faces equidistant from an axis which poles are at one side of a diametral plane through the said axis, the said core structure also including primary and secondary coils surrounding the intermediate pole, a flywheel rotatable about the said axis and having an annular flange formed of magnetic material and at least partly surrounding the core structure, two circularly spaced members of magnetic material directly engaging at their outer extremities with the internal face of the annular flange, the said members being at one side of a diametral plane through the axis of rotation and at least one of them being a radially charged permanent magnet, and two separate pole pieces directly engaging the inner extremities of the respective radially extending members and having arcuate inner faces concentric with the axis of rotation and movable in close proximity to the outer faces of the poles of the core structure which pole pieces cooperate with the radially extending members and with the annular flange of the flywheel to provide a magnetic circuit having inner pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets circularly and toward each other to provide magnetic leakage between them and the said pole"pieces projecting to such extents that the circular width of the gap between them is less than the circular width of the intermediate pole of the core structure.

8. In a flywheel magneto for an internal combustion engine, the combination of a stationary core structure including a plurality of circularly spaced poles having outer faces equidistant from an axis and including primary and secondary generating coils surrounding one of the poles, a flywheel rotatable about the said axis and having an annular flange formed of magnetic material and surrounding the core structure, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets andwheel to provide a magnetic circuit having inner pole faces of opposite polarity and the said pole pieces projecting substantially beyond their respective magnets axially in both directions.

9. In a flywheel magneto for an internal combustion engine, the combination of a stationary core structure including a plurality of circularly spaced poles having outer faces equidistant from an axis and including primary and secondary generating coils surrounding one of the poles, a flywheel rotatable about the said axis and having an annular flange formed of magnetic material and surrounding the core structure, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of rotation and movable in close proximity to the outer faces of the poles of the core structure which pole pieces cooperate with the magnets and with the annular flange of the flywheel to provide a magnetic circuit having inner pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets axially in both directions and also projecting substantially beyond the respective magnets circularly in both directions.

10. In a flywheel magneto for an internal combustion engine, the combination of a rotatable shaft, a stationary core structure including three circularly spaced poles having outer faces equidistant from the axis of the shaft which poles are at one side of a diametral plane through the axis of the shaft, the said core structure also including primary and secondary generating coils surrounding the intermediate pole, a flywheel formed of magnetic material and including a disc-like portion secured to the shaft and also including an integral annular flange surrounding the core structure, means for magnetically insulating the annular flange of the flywheel from the core structure, two permanent magnets directly engaging at their outer extremities with the internal face of the annular flange which magnets are oppositely charged radially, the said magnets being at one side of a diametral plane through the axis of rotation and being circularly spaced from each other to an extent substantially greater than the width of the intermediate pole of the core structure, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of the shaft and movable in close proximity to the outer pole faces of the core structure which pole pieces cooperate with the magnets and with the annular flange of the flywheel to provide 9, magnetic circuit having inner pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets axially and in both directions and the said pole pieces also projecting substantially beyond their respective magnets circularly and in both directions and projecting toward each other to such extents that the circular width of the gap between them is less than the circular width of the intermediate pole of the core structure.

11. A rotor for a flywheel magneto comprising in combination, a rotatable flywheel adapted to be secured to an engine shaft and including an annular flange formed of magnetic material and having an internal face, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotation and being oppositely charged radially, and two separate circularly spaced pole pieces carried by the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of rotation which pole pieces cooperate with the magnets and with the annular flange to provide a, magnetic circuit having inner pole faces of opposite polarity.

12. A rotor for arflywheel magneto including in combination, a rotatable flywheel adapted to be secured to an engine shaft and including a circularly extending connecting member formed of magnetic material and having an internal face, a radially charged permanent magnet directly engaging at its outer extremity with the internal face of the connecting member, and

means connected with the inner extremity of the permanent magnet and with the magnetic com necting member and providing two circularly spaced pole faces of opposite polarity which faces are at one side of a diametral plane through the axis of rotation.

13. A rotor for a flywheel magneto comprising in combination, a flywheel formed of magnetic material and including a disc-like portion adapted to be secured to an engine shaft and also including an integral annular flange, two circularly,

spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotation and being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective magnets and having arcuate inner faces concentric with the axis of rotation which pole pieces cooperate with the magnets and with the annular flange to provide a magnetic circuit having inner pole faces of opposite polarity.

14. A rotor for a flywheel magneto comprising in combination, a rotatable flywheel adapted to be secured to an engine shaft and including an annular flange formed of magnetic material and having an internal face, two circularly spaced permanent magnets directly engaging at their outer extremities with the internal face of the annular flange, the said magnets being at one side of a diametral plane through the axis of rotation and being oppositely charged radially, and two separate circularly spaced pole pieces directly engaging the inner extremities of the respective mag nets and having arcuate inner faces concentric with the axis of rotation which pole pieces cooperate with the magnets and with the annular flange to provide a magnetic circuit having inner pole faces of opposite polarity, the said pole pieces projecting substantially beyond their respective magnets axially in both directions and also projecting substantially beyond their respective magnets circularly in both directions.

RUSSELL E. PHELON.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 778,707 Reichenbach Dec. 27, 1904 2,101,392 Harmon Dec. 7, 1937 2,245,268 Goss June 10, 1941 

